Water leaked from toilet on second story

[David A.]

My parents came home to find that the upstairs bathroom had a leak from one of the bolts not being tight enough. The water leaked through the edges of the vinyl floor and now there is a big water stain on in the ceiling in the downstairs kitchen. I can try repainting the wet spot but I want a permanent fix and don't want it to rot overtime. What could i do in this case?

I have added a pic for you guys to see
thanks!
http://i1306.photobucket.com/albums/s573/daverealestatetx/IMG_0539_zpscd761a53.jpg